Frank e



(No ModeL) -,F. E. POOL.

RHEOSTAT.

Patented Mar. 29, 1898.

UNITED STATES PATENT OFFICE.

FRANK E. POOL, OF QUINOY, ILLINOIS, ASSIGNOR TO THF. SMITH-HILL ELEVATORCOMPANY, OF SAME PLACE.

RH EO STAT.

SPECIFICATION forming part of Letters Patent No. 601,588, dated March29, 1898.

Application flied January 31; 1393 Serial NO- 668,603- (No model.)

To @ZZ whom it may concern:

Be it known that I, FRANK E. POOL, a citizen of the United States,residing at Quincy, in the county of Adams and State of Illinois, haveinvented certain new and useful Improvements in Rheostats, of which thefollowing is a full, clear, and exact description, reference being hadto the accompanying drawings, forming part of this specification.

My invention relates to an automatic rheo stat, and is particularlydesigned for use in connection with reversible motors forelectricelevator service.

It has for its object the furnishing of a device of simple constructionwhich will secure perfect contact at all times, prevent sparking, andreduce the consumption of the electric current to a minimum. Itpossesses features of novelty herein fully described, and speciiicallypointed out in the claims.

Referring to the drawings, Figure I shows in side elevation a plan viewof my improvement, parts thereof being broken away. Fig. II shows anedge view of the three-arm lever. Fig. III shows an edge view of thelink connection between one arm of the said lever and the dash-pot. Fig.IV shows an edge view of the roller-wheel, through which contact is madebetween the flexible cable carrying the feed-wire and theresistance-coils.

1 represents the solenoid, suitably supported in a casing 2, butinsulated therefrom by the rubber insulation 3. A link i connects thesolenoid with the three-arm lever 5, pivoted to the stationary casing 2at 6. To the lower arm of this lever, but insulated therefrom, ispivoted a yoke 7, which embraces a rolling wheel 8. At the connectionbetween this yoke and the arm is a binding-post 9, which secures the endof a iieXible cable 10, completing the armature-circuit to the motor.

11 are a series of pins secured to the plate 12. Each pin is connectedto a wire 13, which in turn lead to a resistance-coil 14.

The wheel S is toothed, so as to bring the cut-out portions coincidentwith the pins 11. As it rolls over the pins 11 the resistancecoils 14Eare in succession cut out. By this means I provide a rolling metalcontact, dispensing with the sliding brush. The contact is maintained bythe mere weight of the wheel 8, thus dispensing with the necessity ofany tension-spring. There are always two of the pins 11 in contact withthe wheel 8, and as the part 15 leaves the pin quickly the sparking orburning is reduced to a minimum.

1G is a dash-pot whose plunger 16' is connected by a link 17 to thethree-arm lever 5, which cushions the pressure on the opposite endconnected with the solenoid.

1S is a regulating-cock.

19 is the wire leading from the resistancecoils, completing with thewire 10 the armature-circuit to the motor. 2O and 2l complete thefield-circuit through the solenoid to the motor.

In operating the device a current is passed through the solenoid 1 bymeans of the wires 2O 21 and the lever 5 swung as desired. rPhe dash-pot1G serves to cushion the pressure. The lever 5, by means of the yoke 7,carries the wheel S backward or forward over the pins 11 and carries thearmature-current over the wires 10 19 to the motor.

A particular advantage possessed by constructinga rheostat as I havedescribed is that I do away entirely with the usual flat plates ofcopper and the sliding carbon brush. The slow motion required in theautoma-tic rheostat causes the said carbon brush to leave the edge ofthe contact-plate so slowly that sparking takes place and causes burningthereof. Such plates, consequently, become rough and wear the brushrapidly. I am also able to dispense with any spring adjustment, whichhas heretofore been necessary. Moreover, the rolling wheel which I haveprovided gives anew surface of contact with each tooth, and thus avertsthe danger of heating so liable with a sliding brush in constantcontact.

Vhat I claim as new, and desire to secure by Letters Patent of theUnited States, is, in an improved automatic rheostat- 1. The combinationof a feed-wire terminal, a pivoted lever having one end in engagementwith said terminal, stationary contactpins, and a roller linked to saidlever and terminal, and adapted to rest on said contactpins,substantially as described.

2. The combination of a roller, a solenoid, a dash-pot, a three-armlever in connection with said roller, solenoid and dash-pot, and

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resistance-coils consisting;` of a pivoted lever having one end inengagement with said terminal, a plurality of contact-pins connectedwith said resistance-coils, and a roller connected with said terminaland adapted t0 come in Contact with said pins, substantially asdescribed.

FRANK E. POOL.

Witnesses:

CHARLES W. SAHLAND, HARRY G. HENDERSON.

